AN ATTEMPT was made to develop a histoplasmin patch test similar to the tuberculin patch test. Since many analogies exist between histoplasmosis and tuberculosis, such a test was expected to be practicable.
Histoplasmin patch tests were prepared in the following way: 16 square centimeters of thin filter paper was saturated with a solution consisting of 0.5 cc. of undiluted histoplasmin (obtained from Hixon Memorial Laboratory, University of Kansas Hospital, United States Public Health Service, Kansas City, Kan.) and 0.2 cc. of pure glycerin. After drying, the filter paper was cut into small squares, each 25 square millimeters in size.
The patch tests were applied for forty-eight hours to the skin of 64 children who were positive reactors to the intracutaneous histoplasmin test.1 The skin reactions were read after removal of the patches and forty-eight hours later. None of the children showed a positive reaction to the histoplasmin patch test.